This invention relates to an improved trailer hitch for vehicles and the like, and more particularly it relates to a coupling or hitch adapted to connect a draft vehicle to a drawn vehicle wherein the coupling includes a drawbar extending from one of the vehicles and having an eye mounted thereon adapted to be received within a female coupling portion extending from the other vehicle, and wherein a pintle is provided to unite and couple the eye with the female coupling.
Eye and pintle coupling arrangements for hitching a trailer to a tractor or the like are well known in the art. These arrangements are generally simple, reliable and facilitate rapid engagement and disengagement. However, the so-called pintle hook is subject to metal-to-metal wear and, because of the slack in the hitch, it is susceptible to shock and a noisy bang-bang effect during starts and stops. This condition is particularly prevalent and exaggerated when the hitch is used to couple a plurality of vehicles or carts in a train-like arrangement.
The prior art has sought to overcome the aforementioned disadvantages in the conventional pintle hook by providing various means for absorbing these shocks and preventing the metal-to-metal wear. Generally, this has been accomplished, to a limited extent, simply by taking up the slack in the coupling and maintaining the pintle in abutting relation against an inner edge of the eye. For example, in U.S. Pat. No. 1,875,969 issued to D. S. Weiss, a jack arrangement is provided to press the pintle hook tightly against the eye.
Because jack arrangements of the aforementioned type did not provide sufficient flexibility during operation, the prior art then provided various resilient devices for yieldingly maintaining the pintle in abutting relation against a portion of the hook. For example, U.S. Pat. No. 2,370,679, issued to L. A. Martinelli et al., disclosed an hydraulic shock absorber for accomplishing the intended result. Similarly, U.S. Pat. No. 2,984,502, issued to B. I. Tyrrell, disclosed a spring arrangement for providing the resilient restraint. A resilient cushion accomplished the same results in the device disclosed in U.S. Pat. No. 3,531,141 issued to T. B. Dalton.
It should be apparent, however, that in each of the aforementioned prior art devices there will still be a certain amount of metal-to-metal wear between the pintle and the eye even though the slack in the coupling has been taken up by means of the particular arrangement disclosed. This problem was addressed in U.S. Pat. No. 2,998,268, issued to C. P. Witter, which provided a "friction material" which is both hard and has a high coefficient of friction (e.g., brake lining material) to completely surround the pintle and thus prevent metal-to-metal wear against the eye. The pintle is then securely tightened into the eye by suitable jack means. The pintle is, in effect, journaled in the eye for rotation in the horizontal plane; however, the hitch cannot be articulated in the vertical plane, and thus a separate pivotable connection must be provided to accomplish flexing in the vertical plane so as to enable the vehicle to negotiate ramps and the like. It should be apparent, therefore, that the device disclosed in the Witter patent is both complicated and expensive, not only becuase of the need for the separate pivotable connection, but also because of the high cost of the required bearing lining material which is subject to excessive wear in the particular construction disclosed.